Frequency stabilizing device



April 26, 1949- G. G. BRucK FREQUENCY STABILIZING' DEVICE Filed April 9, 1946 VVE/VTM G60/rsf 6. Mac/r Patented Apr. 26, 1949 2,468,029 v FREQUENCY STABILIZING DEVICE George G. Bruck, East Orange, N. J., assignor to )Raytheon Manufacturing Company, Newton, Mass., a corporation of Delaware Application April 9, 1946, Serial No. 660,597

(Cl. Z50- 36) l Claims.

This invention relates to apparatus for stabilizing the frequency of a carrier wave, for example, the carrier wave generated at the master terminal station of a frequency-modulated radio communication system.

Examples of the type of apparatus to which the present invention relates are found in the copending applications of George G. Bruck and Philip E. Volz, entitled Frequency stabilizing system, Ser. No. 647,008, filed February l2, 1946, of George G. Bruck and Paul J. Pontecorvo, entitled Frequency stabilizing system, Ser. No. 655,074, filed March 18, 1946, Patent No. 2,462,841, issued March l, 1949, and of George G. Bruck, Robert M. Sprague and Malcolm C. Vosburgh, entitled Radio communication system, Ser No. 660,596, led April 9, 1946.

While the devices disclosed in said copending applications have been found efficiently to perform their intended functions, they are more or less complicated, and are critical in their adjustment.

It is, therefore, the main object of the present invention to provide frequency-stabilizing apparatus which is simpler than that heretofore proposed for the purpose, and which is easier to set up and adjust.

rIhese, and other objects of the present invention, which will become more apparent as the detailed description thereof progresses, are attained, briefly, in the following manner:

'I'he present invention provides means, in the form, for example, of appropriate wave-guiding apparatus, for deriving from the carrier wave t0 be stabilized two carrier-wave portions of like phase. One of these carrier-wave portions is mixed with an intermediate-frequency wave to produce sideband waves, said intermediate-frequency wave being generated by a novel oscillation generator hereinafter more fully referred to. The other carrier-wave portion is mixed with one of said sideband waves to recover said intermediate-frequency wave. The two mixing devices may comprise non-linear inpedances, such as crystals.

Said mixing devices are connected, respectively, to the output and input circuits of a broad-band amplifying device the center frequency of which corresponds to the frequency of the aforementioned intermediate-frequency wave. This amplifying device is caused to oscillate and produce said intermediate-frequency wave by positive feedback between its output and input circuits, said feedback being obtained by interposing between the mixing devices conv nected, respectively, to said output and input circuits a tuned circuit, for example, a cavity resonator which is resonant to one of the sideband waves produced by the combination of the first above-mentioned carrier-wave portion and said intermediate-frequency wave.

A portion of said intermediate-frequency wave is applied to means, such as a frequency discriminator, for deriving from said intermediatefrequency wave a unidirectional output whose amplitude and sense are functions, respectively, of the magnitude and sense of any deviation of the frequency of said intermediate-frequency wave from its initial frequency, such deviation being brought about, as will hereinafter be more fully explained, by any deviation of the frequency of the carrier wave from its initial frequency.

Finally, the unidirectional output thusy obtained is applied to any appropriate device, electronic or mechanical, for altering the frequency of the source of said carrier wave to compensate for -any such frequency deviation.

In the accompanying specification there shall be described, and in the annexed drawing shown, an illustrative embodiment of the frequencystabilizing system of the present invention. It is, however, to be clearly understood that the present invention is not to be limited to the details herein shown and described for purposes of illustration only, inasmuch as changes therein may be .made without the exercise of invention,

and within the true spirit and scope of the claims hereto appended.

In said drawing, the single figure is a partial block, partial schematic diagram of a frequencystabilizing system assembled in accordance with the principles of the present invention, certain of the components of said system being appropriately broken away more clearly to show internal construction. y

Referring now more in detail to the aforesaid illustrative embodiment of the present invention, with particular reference to the drawing illustrating the same, the numeral I0 designates an oscillator adapted to generate a carrier wave we, preferably, in the microwave region of the electromagnetic spectrum, having a frequency, for example, of 10,000 mc./sec. It is the frequency of this carrier wave that it is desired to stabilize.

The output of the oscillator l0 is applied to an energy-transmission system, for example, a wave guide Il, at the outer end of which (not shown) there may be connected any appropriate load device, for example, an electromagnetic horn adapted to radiate said carrier Wave.

By means of suitable coupling devices, such as probes I2 and I3, two carrier-wave portions 0f like phase are fed from the Wave guide Il into a pair of wave-guide sections lll and l5. The wave-guide sections I4 and l5 also communicate with a cavity resonator I6, respectively, through openings l1 and I8, said cavity resonator being tuned to a sideband wave having a frequency which is either the sum of or the difference between the frequency of the carrier wave wh, generated by the oscillator IIJ, and the frequency of an intermediate-frequency wave w1, generated as will hereinafter be more fully explained. Assuming that the intermediate-frequency wave has a frequency of 50 mts/sec., the cavity resonator IB may be tuned to a frequency of either 10,050 mc./sec. or 9,950 mc./sec. For the purposes of this specification, it will be assumed that said cavity resonator is tuned to the frequency of the upper sideband wave wiwi-wz.

Disposed in the wave-guide sections IA and l5 are non-linear impedance devices, for example, crystals I9 and 20, the former being connected to the input terminals of an amplifying device 2l, and the latter being connected to the output terminal of said device.

Assuming, for the moment, that the amplifying device 2! is feeding an intermediate-frequency wave w1 to the crystal 20, said intermediate-frequency wave will combine with the carrier wave portion wn `entering the wave-guide section l5 from the Wave guide Il to produce sideband waves whim. The upper sideband wave thus produced will enter the cavity resonator I6, which is tuned thereto, and will pass from said cavity resonator to the wave-guide section it to excite the crystal I9. The latter will also be excited by the carrier wave portion wh entering the waveguide section I4 from the wave guide Il to reproduce, across the crystal l0, the intermediatefrequency wave w1. The latter, being applied to the input terminals of the amplifying device 2l, will cause the cycle just described to continue, provided the energy fed back from the output terminal of the amplifying device to the input terminal thereof is of the proper phase to sustain oscillation.

This condition is satised if:

nem ma (2) where Mwh-l-wz) is the frequency deviation of the sideband wave from the frequency to which the cavity resonator i6 is tuned, wn--wz is the resonant frequency of said cavity resonator, and Qc is the Q of the cavity resonator;

And,

where Aoi is the frequency deviation of the intermediate-frequency wave from the frequency to which the amplifying device 2| is tuned, w1 is the resonant frequency of said amplifying device,

and Qa is what might Ibe termed th-e equivalent Q of said amplifying device.

Now, inasmuch as Thus, if the frequency of the carrier wave wh changes by Awb, due to random drift of the oscillator i0, the frequency of the intermediate-frequency wave w1, generated by the oscillating 'amplifying device 2 l, changes by Aoi in accordance with the ratio expressed by Equation 5.

In order to utilize any change in the frequency of the intermediate-frequency wave w1 to stabilize the oscillator i0, `a portion of the output of the amplifying device 2l is applied to a conventional frequency discriminator 22 Whose center frequency corresponds to the initial or normal frequency of the intermediate-frequency wave, and as the frequency of said intermediate-frequency wave varies in response to deviations from the initial or normal frequency of the carrier wave, a unidirectional output is produced having an amplitude and sense which are functions, respectively, of the magnitude and sense of said frequency deviation.

Said unidirectional output is applied to any appropriate control device 23 designed, in turn, to retune the oscillator i0 so as to compensate for the aforesaid frequency deviation.

This completes the description of the aforesaid illustrative embodiment of the present invention. It will be noted from all of the foregoing that the frequency stabilizing apparatus of the present invention is relatively simple in its component parts, requires less skill initially to set up the same than devices heretofore known for similar purposes, and is not as critical to adjust as the heretofore known devices.

Other objects and advantages of the present invention will readily occur to those skilled in the art to which the same relates.

What is claimed is:

1. Apparatus for stabilizing the frequency of a carrier wave comprising: means for deriving from said carrier wave two carrier-Wave portions of like phase; means for mixing one of said carrier-wave portions with an intermediate-frequency wave to produce a sideband wave; means for mixing the other of said carrier-wave portions with said sicleband wave to recover therefrom said intermediate-frequency Wave; an amplifying device, resonant to said intermediatefrequency Wave, and having output and input circuits coupled, respectively, to said rst and second-named mixing means; means, resonant to said sideband wave, for transmitting the same between said first and second-named mixing means, whereby said amplifying device is caused to oscillate at the frequency of said intermediate-frequency wave; means, receptive of a portion of said intermediate-frequency wave, for deriving therefrom a unidirectional output whose amplitude and sense are functions, respectively, of the magnitude and sense of any deviation of the frequency of said carrier wave from its initial frequency; and means, receptive of said unidirectional output, for altering the frequency of said carrier wave to compensate for any such frequency deviation.

2. Apparatus for stabilizing the frequency of a carrier wave comprising-I means, including a wave guide receptive of said carrier wave, a pair of Wave-guide sections, and a coupling device inter` mediate each of said wave-guide sections and said wave guide, for deriving from said carrier wave two carrier-wave portions of like phase; means for mixing one of said carrier-Wave portions with an intermediate-frequency wave to produce a side-band wave; means for mixing the other of said carrier-wave portions with said sideband Wave to recover therefrom said intermediate-freqency wave; an amplifying device, resonant to said intermediate-frequency Wave, and having output and input circuits coupled, respectively, to said first and second-named mixing means; means, resonant to said sideband wave, for transmitting the same between said first and second-named mixing means, whereby said amplifying device is caused to oscillate at the frequency of said intermediate-frequency wave; means, receptive of a portion of said intermediate-frequency wave, for deriving therefrom a unidirectional output whose amplitude and sense are functions, respectively, of the magnitude and sense of any deviation of the frequency of said carrier wave from its initial frequency; and means, receptive of said unidirectional output, for altering the frequency of said carrier Wave to compensate for any such frequency deviation.

v3. Apparatus for stabilizing the frequency of a carrier Wave comprising: means, including a Wave guide receptive of said carrier wave, a pair of wave-guide sections, and a coupling device intermediate each of said wave-guide sections and said Wave-guide, for deriving from said carrier wave two carrier-wave portions of like phase; a non-linear impedance device, disposed in one ofrsaid Wave-guide sections, for mixing one of said carrier-Wave portions with an intermediatefrequency wave to produce a sideband wave; another non-linear impedance device, disposed in the other of said wave-guide sections, for mixing the other of said carrier-wave portions with said sideband wave to recover therefrom said intermediate-frequency wave; an amplifying device, resonant to said intermediate-frequency Wave, and having output and input circuits coupled, respectively, to said first and second-named impedance devices; means, resonant to said sideband wave, for transmitting the same between said wave-guide sections, whereby said amplifying device is caused to oscillate at the frequency of said intermediate-frequency Wave; means, receptive of a portion of said intermediate-frequency wave, for deriving therefrom a unidirectional output whose amplitude and sense are functions, respectively, of the magnitude and sense of any deviation of the frequency of said, carrier wave from its initial frequency; and means, receptive of said unidirectional output, for altering the frequency of said carrier wave to compensate for any such frequency deviation.

4. Apparatus for stabilizing the frequency of a carrier wave comprising: means, including a wave guide receptive of said carrier wave, a pair of wave-guide sections, and a coupling device intermediate each of said wave-guide sections and said wave-guide, for deriving from said carrier wave tWo carrier-Wave portions of like phase; means, disposed in one of said wave-guide sections for mixing one of said carrier-wave portions with an intermediate-frequency wave to produce a sdeband wave; means, disposed in the other of said wave-guide sections, for mixing the other of said carrier-wave portions with said sideband wave to recover therefrom said intermediatefrequency wave; an amplifying device, resonant to said intermediate-frequency wave, and having output and input circuits coupled, respectively, to said first and second-named mixing means; a cavity resonator, resonant to said sideband wave, for transmitting the same between said' first and second-named mixing means, whereby said amplifying device is caused to oscillate at the frequency of said intermediate-frequency wave; means, receptive of a portion of said intermediate-frequency wave, for deriving therefrom a unidirectional output whose amplitude and sense are functions, respectively, of the magnitude and sense of any deviation of the frequency of said carrier wave from its initial frequency; and means, receptive of said unidirectional output, for altering the frequency of said carrier wave to compensate for any such frequency deviation.

5. Apparatus for stabilizing the frequency of a carrier wave comprising: means, including a wave guide receptive of said carrier wave, a pair of wave-guide sections, and a coupling device intermediate each of said wave-guide sections and said wave guide, for deriving from said carrier wave two carrier-wave portions of like phase; a nonlinear impedance device, disposed in one of said Wave-guide sections, for mixing one of said carrier-wave portions with an intermediate-frequen-cy Wave to produce a sideband wave; another non-linear impedance device, disposed in the other of said wave-guide sections, for mixing the other of said carrier-wave portions with said sideband wave to recover therefrom said intermediate-frequency wave; an ampiifying device, resonant to said intermediate-frequency wave, and having output and input circuits coupled, respectively, to said first and second-named impedance devices; a cavity resonator, resonant to said sideband wave, for transmitting the same between said wave-guide sections, whereby said amplifying device is caused to oscillate at the frequency of said intermediate-frequency wave; a frequency-discriminator, receptive of a portion of said intermediate-frequency Wave, for deriving thererfom a unidirectional output Whose amplitude and sense are functions, respectively, of the magnitude and sense of any deviation of the frequency of said carrier wave from its initial frequency; and means, receptive of said unidirectional output, for altering the frequency of said carrier wave to compensate for any such frequency deviation.

6. An oscillation generator comprising: means, receptive of a first periodic wave, for deriving therefrom two periodic-Wave portions of like phase; means for mixing one of said periodicwave portions with a second periodic Wave t0 produce a third periodic wave whose frequency is an arithmetic function of the frequencies of said rst and second periodic waves; means for mixing the other of said periodic wave portions with said third periodic wave to recover therefrom said second periodic wave; an amplifying device, resonant to said second periodic wave, and having output and input circuits coupled, respectively, to said rst and second-named mixing means; and means, resonant to said third periodic wave, for transmitting the same between said first and second-named mixing means, whereby said amplifying device is caused to oscillate at the frequency of said second periodic wave.

'7. An oscillation generator comprising: means, including a wave guide receptive of a rst periodic wave, a pair of wave-guide sections, and a coupling device intermediate each of said waveguide sections and said wave guide, for deriving from said first periodic wave two periodic-wave portions of like phase; means for mixing one of said periodic-wave portions with a second periodic wave to produce a third periodic wave whose frequency is an arithmetic function of the frequencies of said first and second periodic waves; means for mixing the other of said pe riodic-wave portions with said third periodic wave to recover therefrom said second periodic wave; an amplifying device, resonant to said second periodic wave, and having output and input circuits coupled, respectively, to said first and second-named mixing means; and means, resonant to said third periodic-wave, for transmitting the same between said first and secondnamed mixing means, whereby said amplifying device is caused to oscillate at the frequency of said second periodic wave.

8. An oscillation generator comprising: means, including a wave guide receptive of a first periodic wave, a pair of wave-guide sections, and a coupling device intermediate each of said waveguide sections and said wave guide, for deriving from said first periodic wave two periodicwave portions of like phase; a non-linear impedance device, disposed in one of said wave-guide sections for mixing one of said periodic-wave portions with a second periodic wave to produce a third periodic wave whose frequency is an arithmetic function of the frequencies of said rst and second periodic Waves; another non-linear impedance device, disposed in the other of said wave-guide sections, for mixing the other of said periodic-wave portions with said third periodic wave to recover therefrom said second periodic Wave; an amplifying device, resonant to said second periodic wave, and having output and input circuits coupled, respectively, to said rst and second-named impedance devices; and means, resonant to said third periodic wave, for transmitting the same between said wave-guide sections, whereby said amplifying device is caused to oscillate at the frequency of said second periodic wave.

9. An oscillation generator comprising: means, including a wave guide receptive of a first periodic wave, a pair of wave-guide sections, and a coupling device intermediate each of said waveguide sections and said wave guide, for deriving from said first periodic wave two periodic-wave portions of like phase; means, disposed in one of said wave-guide sections, for mixing one of said periodic-wave portions with a second periodic wave to produce a third periodic wave whose frequency is an arithmetic function of the frequencies of said first and second periodic waves; means, disposed in the other of said wave-guide sections, for mixing the other of said periodic-wave portions with said third periodic wave to recover therefrom said second periodic wave; an amplifying device, resonant to said second periodic wave, and having output and input circuits coupled, respectively, to said first and secondmamed mixing means; and a cavity resonator, resonant to said third periodic wave, for transmitting the same between said first and second-named mixing means, whereby said amplifying device is caused to oscillate at the frequency of said second periodic wave.

10. An oscillation generator comprising: means, including a wave guide receptive of a first periodic wave, a pair of wave-guide sections, and a coupling device intermediate each of said waveguide sections and said wave guide, for deriving from said first periodic wave two periodicwave portions of like phase; a non-linear impedance device, disposed in one of said waveguide sections, for mixing one of said periodicwave portions with a second periodic Wave to produce a third periodic wave whose frequency is an arithmetic function of the frequencies of said rst and second periodic waves; another non-linear impedance device, disposed in the other of said wave-guide sections, for mixing the other of said periodic-wave portions with said third periodic wave to recover therefrom said second periodic wave; an amplifying device, resonant to said second periodic Wave, and having output and input circuits coupled, respectively, to said `first and second-named impedance devices; and a cavity resonator, resonant to said third periodic wave, for transmitting the same between said wave-guide sections, whereby said amplifying device is caused to oscillate at the frequency of said second periodic Wave.

GEORGE G. BRUCK.

REFERENCES CITED The following references are of record in the i-lle o' this patent:

UNITED STATES PATENTS 

